WASHINGTON (CNN) --As Iraq considers whether to accept the conditions in the U.N. Security Council resolution passed Friday, Pentagon officials are preparing for the possibility of war if Saddam Hussein refuses to disarm.

President Bush has not approved a final war plan, officials have told CNN, but several scenarios are being considered.

One plan involves what Pentagon officials and military analysts call a 21st century blitzkrieg -- referring to the surprise attacks involving aircraft and fast-moving armor used by Germany at the beginning of World War II.

Sources said that in that strategy, the United States and its allies would launch a ferocious opening air assault involving hundreds, or possibly thousands, of all-weather, satellite-guided bombs and cruise missiles combined with covert missions and psychological operations.

The goal, the sources said is to demoralize Saddam's generals and discourage them from following orders to unleash chemical or biological weapons.

Officials are concerned that the Iraqi president could order the use of chemical or biological weapons if he feels that his regime is threatened.

Analysts said the current plan targets the "centers of gravity" that keep him in power -- his weapons of mass destruction, the Republican Guard and his presidential palaces.

Officials estimate that invading Iraq would involve 80,000 to 250,000 U.S. troops which will have to come from the United States and bases in Europe.

There are currently about 27,000 U.S. troops in the region.

Pentagon sources said that it was unlikely that the necessary troops and their equipment could be moved into position before February. That would also give U.S. assembly lines more time to replenish the military stocks of highly accurate J-DAM 2,000 pound bombs that have been very effective in the war in Afghanistan.